Apparatus for grinding materials



Jan. 1, 1924 l N. c. JOHNSON APPARATUS FOR GRINDING MATERIALS Filedsept. lo 1921 2 sheets-sheet 1 y l l w16/ y v mmamtoz ../za/a 6705125012@51j @Hom/w1# t Jan. 1, 1924 N. C. JOHNSO N APPARATUS FOR GRINDINGMATERIALS 2 Sheets-Sheet 2 Filed Sept. l0 1921 patented dan. ll, i924'.

intacta PATENT FFHCE.

NATHAN C. JOHNSON, OF ENGLEWOOD, NEW JERSEY.

APPARATUS FOR GRINDING MATERIALS.

Application led September 10, 1921. Serial No. 499,766.

concern:

I, NATHAN C. JoHNsoN, a citizen of the United States, and a resident ofEnglewood, county of Bergen, and State of New Jersey, have inventedcertain new and useful Improvements in Apparatus for Grinding Materials,of which the following is a specification. f

The invention relates to apparatus for grinding various substances.

Heretofore, grinding in ball mills has frequently been accomplished bymeans of large quantities of pebbles or balls of relatively largediameter andv mass, falling under the acceleration of gravity from aposition adjacent a high point of a revolvcontainer down upon otherpebbles o r To all whom t may Be it known that in bals and upon thematerials to be comminuted. Such mills are bulky in size, require muchpower and are slow in action, for several reasons; large masses of largepebbles are necessary to secure adequate grinding, entailing largeunits, a large part of the charge must be lifted idly in the containerbefore falling in useful work, and, since the pebbles are large, theuseful points of contact are relatively few in number, with consequentslow action on ground. rl`he present invention overcomes these and otherdisadvantages, and effects grinding of desired substances in aneffective and improved manner, by the apparatus hereinafter described.

ln the invention, in its preferred aspect, use is made of a relativelygreat number of permanent grinding bodies, each of small mass but witha. correspondingly large number of points of contact, and having akinetic energy, by reason of high-velocity mass flow, comparable to thatof fewer balls of larger mass falling by gravity. The material to beground is min led with these small grinding bodies or bal s, and thecombined mass caused to move rapidly, with rapidly changing velocity,along one or more paths rapidly wherechanging in direction, bycompacting of the mass. violent-interparticle attrition, and a rapid andthorough comminuting of the material to be ground are effected. Theseresults are produced by subjecting the mass to, such centrifugal forceas to give it compact high-velocity mass flow, and diverting the flowinwardly atinthe materials to be with changing velocities of allportervals these effects taking place tions 0f the mass, in continuouscycles, actions arev produced and brought about.

Various useful and improved e'ects and features of the invention will bemore jfully described hereinafter.

The principal object of the invention is the production of novel andeiiicient appa'- ratus for grinding various materials.

The invention consists yin the novel features and combinations of partshereinafter shown and described in their preferred forms; and theinvention is more particularly set forth in the appended claims.

Further objects and advantages of the invention will more fully appearfrom the following description and the accompanying drawingsillustrating the preferred form of apparatus comprised within theinvention.

In order that the invention may be more clearly understood attention ishereby directed to the accompanying drawings illustrating the preferredform of apparatus.

Referring to the drawings:

Fig. l is a vertical sectional view of grinding apparatus embodying thereferred form of apparatus comprised within my in-l vention, thissection being taken on line 1-1 of Fig. 2; y

Fig. 2 is a horizontal section taken on line 2-2 of Fig. l;

Fig. 3 is an enlarged view of a mass defleeting' blade used intheapparatus together with supporting means therefor; and

Fig. 4 is a section taken on line 4-4 of Fig. illustrating additionallya portion of the revolving bowl or container.

Fig. 5 is an enlarged detail of construction showing in vertical sectionthe edge portion of the rim of the bowl and the stationary cover withthe inclined fan blades secured to the outer surface of the bowl,

and

Fig. 6 is a vertical section taken on line whereby the desired of itsdiameter being effective. The bowl is preferably made up in sections,and it may, as shown, consist of a bottom lsection 2 and an uppersection 3, preferably formed of hard metal such as manganese steel. Thelower section 2 may be provided with an olf-set iange 4 so as to providea shoulder 4l for receiving the upper section 3. The sections may besecured together in any suitable manner as by bolts 5 extending throughthe flange 4 of the lower section and an outwardly formed flange 6 onthe upper section.

The bowl may berotated in'any suitable manner as by means of a beveledgear 7 on shaft 8, gear 7 engaging with a beveled gear 9 formed on amember 10 which is centrally secured to the under side of the bowl bysuitable means such as bolts 11. Shaft 8 is suitably supported bybearings 12, 12, shaft 8 being rotated in any suitable manner from anelectric motor or other source of y power. As shown in the drawingsshaft 8 may be provided with a gear 13 which meshes with a pinion 14which carries a sheave 15 over which runs a driving belt 16.

Member 10 carryin beveled gear 9 is mounted for rotation 1n any suitablemanner. As is indicated in the drawings, member 10 may rest upon abearing within a boss 17 formed on the fixed frame member 18 of themachine. The bowl is provided. with an upwardly extending central cappiece or projection 19. A vertical shaft 2) extends downwardly throughyprojection 19 and through members 10 and 17. This shaft 20 may beprovided with a suitable head at, its upper end and with a washer orlate 21 adjacent its lower end, anti-friction earings 21,1 beingprovided between washer 21 and a lixed member 22 secured within boss 17.f Shaft 20 may be screw-threaded at its lower end and provided with anut 23 for holding washer 21 in engagement with its bearing. Member 10is provided with a downwardly extending central portion 10't 'withinboss 17 which is rotatably mounted on a .ball bearing or other suitableanti-friction bearing 24 above the fixed member 22.

As shown in the drawings the bowl is cov'- ered by a cover plate 25which is supported by brackets 26 extending from upri ht frame members271. of'which any suita le number such as four may be provided mountedat intervals around the bowl.l The cover plate is provided with openingstherethrough through which the dedecting vanes indicated at 27 mayextend, these vanes preferably being pivotally secured each to one ofthe uprights 271, asy by means of the hinged connection indicated at 28.

Means for causing air to sweep into the bowl and to then rise therefromcarrying with it material which has been sucientlv iinely ground, isalso provided in a form Laramie well known to the art of air separation.This may take the'form of a downwardly extending air conduit 29 and anuptake member 30 both mounted in position above the cover plate 25 whichis provided with a suitable opening, the uptake member being centrallyarranged with respect to the bowl and the air intake conduit 29 beingarranged around the same center. Air may be forced downwardly throughconduit 29 by any suitable blower, such as is indicated diagrammaticallyat 31. The belt connection 32 shown in iFig. 1 as extending upwardlyfrom shaft 8 to a shaft 321, is used for operating a mechanism forcontinuously feeding the material to be ground into an opening in theside of the uptake member 30, this not being included in my invention.The feed mechanisln is adjusted to'keep up with the grind' 111g capacityof the mill and the; removal of fine material by the air sweep. v-

The deflecting members indicated generally by reference character 27Vvare preferably hlngedly connected, as stated, to standards 271, so thatthey may be swung upwardly out of the bowl when this is desired for anypurpose such as the renewal of the blades. In the preferred form ofthese deiiecting members each one is provided with a top plate 33 towhich the hinge connection is secured. Each deflecting member isprovided with a downwardly extending deiiecting member 34, which ispreferably cast integral with the top plate 33, this member preferablybeing made fairlv heav and Isubstantial. Member 34 preferab y has aseparate and renewable blade member 35 pivotally secured thereto, blademmeber 35 being preferably formed of steel, or i other suitablematerial, and being adapted to engage against the surface of bowl 1.This renewable blade 35 is pivotally connected to the edge portlon ofblade member 34 by Asuitable means, as by securing member 35, by meansof screws 36, or the llke, to a sleeve member 37 through which extendsa,hinge lpintle, 38, the lower end of which/extends t rough a lug 39adjacent the ybottom of the blade member 34. The top .-,fplate 33 of thecasting is provided with ahollow boss 40 extending upwardly therefromata suitable angle to receive the upper end of pintle 38, plate 33 beingprovided With a Suitableopeningthrough which intleI 38 extends. 'Q'lheupper end of the inge pintle inabe ,received in -a screw plug 41 mountedin t e upper end of the boss 40, j

' container,

acreage service. Blade`35 may be removed by re- -moval of screws 36.

throughout its length. rlhe inner or mass v engaging face 44 of thesubstantial portion 34 of the blade construction is preferably concave`along its length as well as across its width. The renewable blade 35 isso locate and positioned against the side of the bowl as to form anacute angle with the side of the bowl to the rear of the entering edgeof blade 35, the inner face of blade 35 being inclined against thedirection of flow of the mass in the bowl when the latter is rapidlyrotated, as stated. The concave face 44 of blade member 34 serves as acontinuation of the surface of blade 35 to divert the flow of materialfrom the inner surface of the side wall of the bowl toward the center ofthe bowl. The blade member 34 is provided with a short approximatelyhorizontal flange 45 over which a portion of the mass of material willflow as it is diverted inwardly by the curved surface 44 of the bladestructure. rlhe operation of these parts will be more fully describedhereafter. The bot-tom of the bowl is preferably provided with heatabsorbing vanes 46 eX- tending downwardly therethrough, and a stationaryjacket 47 may be provided about the bowl or a portion thereof. With thisconstruction, an external. source of heat (not shown) being any desiredtemperature may be eected, varies 46 serving to absorb the heat and thejacket to conserve the same. Heat may be drected into the jacket throughopening 4 1.

ln the operation of the apparatus, a charge of materials to be groundmay be fed continuouously by appropriate means known to the art into the'revolving container, the material being passed into the for example,through an opening, not shown, in the side of the air uptake 30. Thematerials to be ground and the small steel shot, or other permanentgrinding bodies, will circulate about the container under the influenceof centrifugal force, and will at intervals be diverted or deflectedtowards the center of the container by the deflect-ing blades 35, 34.The mass ,is compacted by the centrifugal force aga-inst the side wallyofthe container until it is `defiected, in continuous cycles, towardsthe center of lthe container, when the material and the grinding bodieswill be dispersed and separated from each other, the form of the masssuc-h as to turn the material'over and spread it out more or less in fanshape as it is diverted away from the sides of the bowl.

provided grinding at deflecting members being' The air which enters thebowl through the conduit 29 willbe given a swirling motion within thebowl partl because of its passage through the spira ly form-ed portion48 of the intake, and partly because ofy the rotation of the bowl.During the dispersion of the steel shot or grinding bodies they will bethoroughly cleansed by this air and the latter leaving the bowl by theuptake passage 30 will carry with it d all of the material which hasbeen ground to suflicient fineness, this finely ground material beingdeposited in a suitable vessel, such as the dust collecting chamberindicated at 49, in well-known manner. After passing into chamber 49 andbeing relieved of its charge of ground material the air is returnedthrough conduit 29 to the bowl, to again take up a charge of groundmaterial, in repeated cycles.

llt will be noted that the small grinding balls, or bodies, togetherwith the material to be ground, travel in a multiplicityI of.

continuous streams traversing defined paths in which breaking, crushingand comminuting of the charge of material is effected by theinterparticle attrition of the material and by the oompacting of themass under the induence of centrifugal force against the walls of thecontainer and against the defiecting blades as the mass passes over thesame. When the mass is deflected by the deflecting vanes its velocity ismomentarily altered, and siderable extent turned over, streams ofmaterial adjacent the upper edge of the bowl being directed downwardlyby each vane encountered and material rising on an inclination, to aconsiderable extent, =being directed upwardly, or permitted to continueits upwardly inclined course, by the vanes, so that upper elements ofthe stream will become lower ones, and lower elements will become upperones. Upper elements move at a higher velocity than lower ones, undercentrifugal force, because of the greater radius of the upper part ofthe bowl. Each portion of the mass, which is at any moment deflectedinwardly will shortly again come under the influence of the centrifugalforce and be accelerated up to a velocity in accordance with itsposition on the side ofthe bowl. Accordingly, if the mass is assumed forconvenience as tilarnented, diering velocities will be imparted to thevarious filaments of the mass, incident to which there will be a violentrubbing of the particles of the mass one against the other and of thepermanent grinding bodies against the material to be ground.

The result of the interparticle attrition described and of thecompacting of the mass, by centrifugal force and diversion, as the masscontinuously circulates, serves to break down and to comminute allparticles of the at the same time it is to a con-v Ulu charge in anextremely rapid and thorough manner so that the charge is reduced torequisite fineness in a very short time. It is obvious that anymaterials either hard or soft may be ground or comminuted by theinvention.

According to the preferred manner of practicing the invention, as forexample in the pulverizing of anthracite coal or of Portland cementclinker, the requisite charge of materials to be ground and therequisite number and amount of grinding bodies, preferably small hardsteel shot, are placed in the bowl.` The quantity of the small balls orgrinding bodies will vary from several pounds to several tons accordingto the size of the machine and the nature of the material to be ground.The charge or rate of introduction of material to be ground will varyaccording to its nature, the size of the unit and the degree ofcomminution desired, but usually the mass of grinding bodies will berelatively great in proportion to the charge being ground.

When the container is in rotation these grinding bodies, or shot, willmove outwardly across the bottom of the container and, under the actionof centrifugal force, upwardly along the outwardly flaring sides of thecontainer until a zone of greatest diameter is reached. At this pointthe greatest velocity is attained, and the speed and centrifugal forceincident to the speed are sufficiently great to produce compacting ofthe mass and high velocity mass flow; ll have found that a peripheralvelocity at the rim of the container of approximately 1500- feet perminute is sufficient to give the'desired flow to the mass when apparatusof the char# acter shown .herein is utilized. Under the momentum of themass 1t 1s caused to circulate at high 'velocity in a steady stream orstreams along one or more predetermined paths (determined by the shapeof the container and the location, number and shape of the stationaryblades or mass deflecting devices) these paths rapidly changing indirection. During the passage of material over each blade or massdeflecting device an intensified compacting of the mass is caused by theretardation of the high velocity mass flow at such point, and throughoutthe process`a violent interparticle attrition is caused as thevelocities of the various portions of the mass are altered by theenforced circulation along the predetermined paths` whereby extremelyrapid violent and thorough grinding of the materialis brought about.

Furthermore, 4as stated above, as the swiftly flowing mass of shot andmore -or less finely ground material leaves each deflecting blade, tofollow' its predetermined path towards the center of the container, themass is spread out fan-wise through the air so as to permit a thoroughcleansing of the Maaate ground material from the grinding bodies and theremoval of the fine material from the bowl with the air, while thegrinding bodies which are too heavy to be thus removed by the air willremainvbehind to be used again and again in repeated cycles.

It is further to be understood that any portion of the charge to beground which is not of sufficient fineness thus to be removed returns,together with the grinding bodies, to a point adjacent the center of thebot-tom of the bowl, from which it again moves outwardly and, as itattains velocity with rotation with the container, upwardly along thesides of the bowl to again be compacted, subjected to high velocity massflow, interparticle attrition, diversion and intensified compacting bythe fixed vanes or blades, spreading and cleansing bypassage through theair after leaving the blades, impingement on the bowl adjacent thecenter thereof, and so on in rapidly repeated cycles.

It is to be understood also that while grinding may thus be effected onthe material continuously fed in and continuously removed, the inventionis equally applicable to the grinding of single charges of material. ltwill also be noted that either wet or dry material may be operated uponand that grinding at any desired temperature may be effected, as statedabove, as for example in the carrying out of solvent or distillationprocesses.

lft will be noted that the grinding medium preferably used comprises arelatively large number of bodies each of small mass, these bodieshaving in operation a considerable kinetic energy because of theirvelocity, the small grinding bodies also, 'because of the considerablenumber of the same used, presenting a multiplicity of points of contactto the material to be ground. Because of the small size of the grindingbodies also, they, together with the charge, constitute a mass which isreadily deflected from its circumferential path around the bowl by meansof thefixed deflecting blades. Accordingly the expenditure `of power isnot sensibly increased-by such diversion of the grinding bodies andcharge, beyond the power reuired to rotate the container and a portionof the charge plus the power required lto accelerate another portion ofthe charge up to aproper velocity.

l It will be further noted that if we consider the crushing of a lump orparticle of material at any point in -the path of the materials in thebowl, it is at once evident, since, the grinding medium is one which isdeformable and at the same time is being compacted with pressure dueto'the centrifugal force, that the crushing of any lump of material isat once followed up closely by the deformable medium to immediatelyproduce finer crushing, the grinding medium lll() bowl in time to passover material between the aaaaaaa constituting in edect a Huid solidhaving a high static pressure and a large number of points of contact,surrounding and pressing upon each portion of the material to be round.

lt will be noted that the constant removal of the finely ground materialpermits increased output for given application of ower in comparisonwith apparatus in which the balls or grinding bodies are cushioned by aconsiderable portion of the fine material retained in the mass.

In further reference to the shape of the deflecting vane in thepreferred form of the invention, it should be said that the lower flangeor shelf 45 serves several purposes. It serves to protect the lower edgeof deflector 34 from wearing away, since an upwardly inclined filamentor portion of the stream of material which would otherwise strike thebottom-edge of -member 34 is deflected from the lower surface of shelf45 without damage, this portion of the stream again rising along thewall of the the shelf 45 of a subsequent blade 34. The portion of thestream which passes above shelf 45 will, in part, be deflecteddownwardly by surface 44 of member 34 against the upper surface of shelf45, fromwhich it must glance, so that the lower edge of the curvedsurface 44 will not be worn by the passage of the material over thesame. At the same time there is an intensified compactin of the materialand attrition of the partie es above each shelf 45, `because of theaction described.

llt should likewise preferred form of construction, esca o rim of thebow and the stationary cover 25 is largely prevented by the provision ofinclined fan blades, indicated at 50, secured to the outer surface ofthe bowl immediately below the upper edge thereof and below the dange 51at the outer edge of the cover (Figs. 1, 5 and 6), these fan bladesbeing arranged as they rotate with the bowl to blow air towards thejoint between the bowl and the cover, and thereby eect an air seal ofthis joint.

While l have described my invention according to the preferred forms ofmachines embodying the same, it will be obvious to those skilled in theart, after understanding my invention, that various alterations,modifications and substitutions may be made without departing from thespirit and scope of the invention, and l aim in the appended claims tocover all such modifications.

1. lln a grinding machine, the combinabe noted that, in the tion of anupright rotatable bowl rotatable l at such speed as to subject thecontents thereof to the action of centrifugal force, and one or morestationary mass deflecting devices positioned adjacent the sides of thebowl each having a mass entering edge extending upwardly towards theupper edge of the bowl, a concave mass deflecting face to the rear ofsaid edge in the direction of movement of the material in the bowl, soas to engage the material adjacent the side of the bowl and deflect itinwardly and a bottom horizontal forwardly extending flange over whichwill flow material directed inwardly by said face. j

2. ln a grinding machine, the combination of an upright rotatable bowlrotatable at such speed as to subject the contents thereof to the actionof centrifugal force, a fixed member adjacent the bowl, and a massdeecting device comprising a plate hinged to said fixed member andextending inwardly over member extending downwardly therefrom within thebowl and a blade having a mass entering edge, pivoted to said curvedmember and spring-pressed into position to cause said edge to extendclosely adjacent to the side of said bowl, said curved member having aconcaved face whereby material within thebowl passing over saidbladewill be deflected away from the side of the bowl.

3. In a grinding machine, the combination of an upright rotatable bowlrotatable at such speed as to subject the contents thereof to the actionof centrifugal force, a fixed member adjacent the bowl, and a massdeflecting device carried by said fixed member, comprising a curvedmember extending downwardly within the bowl and a blade having a massentering edge extending forwardly from said curved member into a pofsition inv which said edge lies closely adjacent tb Allthe side of saidbowl, said blade being removably hinged to said curved member and saidcurved linfiinber having a concaved face whereby material within thebowl passing over said blade will be defiected away from the side of'the bowl.

4. ln a grinding machine, the combination of an upright rotatable bowlrotatable at such speed as to subject the contents thereof to the actionof centrifugal force, a fixed member adjacent the bowl, and a massdeflecting device carried by said fixed member, comprising a curvedmember extending downwardly within the bowl and .a blade having a massentering edge extending forwardly from said curved member into a ositionin which said edge lies closely adlacent to the side of said bowl, saidblade in removably hinged to said curved mem er and said curved memberhaving a mass engaging'face, concaved and inclined inwardly towards thecenter of the bowl, and a bottom horizontal forwardly extending flange,over which will ow material directed inwardly by said face.

5. In a grinding machine, the combinathe rim of the bowl, a curved tionof an upright rotatable bowl rotatable at such speed as to subject thecontents thereof to the action of centrifugal force, a stationary covermember above said bowl, D having an outwardly and downwardly extendingflange, and fan blades secured on the exterior surface of said bowladjacent aimee/ie the upper edge thereof, arranged to force airv againstthe outer edge of the joint between said bowl and cover member. 10

ln testimony whereof, ll have signed my name to this specification.

NATHAN o. JoHNsoN.

